1. Field of the Invention
The present invention relates to a substrate treatment method and a substrate treatment apparatus. Exemplary substrates to be treated include semiconductor wafers, substrates for liquid crystal display devices, substrates for plasma display devices, substrates for FED (Field Emission Display) devices, substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photo masks, ceramic substrates and substrates for solar cells.
2. Description of Related Art
In production processes for semiconductor devices and liquid crystal display devices, a substrate treatment apparatus of a single substrate treatment type adapted to treat a single substrate at a time is used, which includes a spin chuck which horizontally holds a substrate and rotates the substrate, and a nozzle which spouts a treatment liquid toward a center portion of a front surface of the substrate being rotated by the spin chuck.
In a substrate treatment to be performed by the substrate treatment apparatus, a chemical liquid step of supplying a chemical liquid to the front surface of the rotating substrate, and a rinsing step of supplying a rinse liquid to the front surface of the rotating substrate are sequentially performed. Thereafter, isopropyl alcohol (IPA liquid) is supplied to the front surface of the substrate. The rotation speed of the substrate is zero or low when the IPA liquid is supplied. Since no centrifugal force or a smaller centrifugal force acts on the IPA liquid, the IPA liquid is retained on the front surface of the substrate to form a liquid film (this state is hereinafter referred to “puddle-like state”). After the rinse liquid is replaced with the IPA liquid on the front surface of the substrate, the rotation speed of the substrate is increased to spin off the IPA liquid film from the front surface of the substrate to dry the substrate.
JP2009-295910A and JP2009-212408A propose a method in which the puddle-like liquid film of the rinse liquid is retained on the front surface of the substrate (puddle rinsing step) before the IPA liquid film is retained on the front surface of the substrate after the rinsing step in this process sequence. According to these patent documents, the rinsing step is performed with the substrate being rotated at a predetermined liquid treatment rotation speed, and then the rotation speed of the substrate is reduced from the liquid treatment rotation speed to a lower speed. At this time, a smaller centrifugal force acts on the rinse liquid supplied to the substrate. Therefore, the rinse liquid stagnates on the front surface of the substrate, so that the puddle-like rinse liquid film is retained on the entire front surface of the substrate.